Thebmostatic conteol fob elegtbically-heated appabattjs



l A. EWHITTIER THERMoTATIo coNTRoLYPpz EIJEcTnIcALLY HEATH APPARATUS July 3o, 1929. Re. 11,391

original Eiled Dc, 9, 192'? Ava/NTO? Reisaued July 30, 1929.

l'Jl'alTral). STATES Re. 17,391 PATENT QFFICE.

maar n wnrrrrna, or 1anIsror.,.oo1qNnc'rIcU'r.

,rnnnmosra'rroconmaon ron ELEc'raIeALLr-nmrnn arraaarus.

origum Nu. 1,713,578, dama This invention relates to those indicating' thermostatic devices which are provided for controlling the current in the Vcircuits of electrically heated apparatus, suchfor instance as 'electricall heated ranges and ovens, and more particularly controls that are designed to be fastened to the side Walls rather than the front walls or doors of'electrically heated ranges and ovens.

:The object 'of the invention is to provide an.

inexpensive thermostat of the class mentioned that is simple to install and which is readily 'adjusted so that it will control'the tempera ture ofthe apparatus to which it is applied ver closely between the desired maximum an minimum degrees of heat for which it is rated, the temperatures being visually indicated, and the current conductors being so disposed within the device that they always insure the proper current paths without danger of short circuiting and allow the terminals of the circuit wires to be easily attached without disturbin the mechanism and in such manner that t ey will not interfere with the adjustment of 'the current switching.

ymeansor become disengaged or broken ,by

the movements of the current switching means. -l- V In the accompanying drawings which illustrate an embodiment ofthe invention, Fig. 1 shows a side elevation of the mechanism with the casing, ,which comprises a base plate with a tubular stem and a cover, cut in cen- `tral section. Fig. 2 shows an elevation, of

the device with the' front of the cover out away. Fi shows a diametrical' section'of the parts illustrated in Fig. Fig. 4 is a view looking at the outside-of the base plate. Fig. 5 is a view looking intothe cover.- Fig. 6 is a side view of the device with the parts assembled. i

The base plate 1 which is circular is adapt.

ed to be fastened to the side wall of the range, oven or other apparatus towhich the device ,is to be applied. Extendin centrally from the back of the plate is a tu ular stem 2 that is designedy to extend through the wall into the interior of the apparatus, the heat of which is to be controlled. Rotarily su ported bylthe plate and extending through. the stem is a spindle 3 and encircling the inner end of the spindle with an end fastened thereto and an end fastened to the stem is a coiled strip 4 of thermostatic metal. An arm 5 is fasplied.v

.and ooselfy May 21, 1929,`Ser1a1 o. 238,760, nled December 8, 1927. Application f orj relnuc lrled. .Tune 3,1929. Serial K0.. 865,207.'Y l

tened tothe outer end of the s indle so as to extend radiallyl in front of t eplate. A

segmental plate 6 graduated with the degrees i of heat for which the device is rated is fasthe spindle and the outer end ofthe arm 5 is bent forwardto `provide a pointer 7 which will travel over the graduations. The arm 5 carries inside of the aduated late a forwardly extending stu 8 of insu `ating material. v The pointer 7 is caused totravelover the segmental graduated plate by the oscillations of the arm as the spindle is rotated by the action of the thermostatic coil due to variations ofthe heat to which it is subjected in the apparatus to which the device 1s ap- Fastened to therefrom are binding posts 9, 10 and 11. e 0n the back of the plate thesev osts are threaded .the base plate but insulated and provided with nuts 12 orthe attachment xof the terminals of thecircuit wires, which may lead from any common type ofrelay A operated heating circuit switch. On the front of the plate these posts are tubular and movable in the openings are headed contact studs 13, 14,15, normally pressed'forwardby springsl.V Thestud 14 has a. pro'ectingpin 17 which, as `hereinafter' descri ed, is

employed "as a stopte limit the adjusting movements of the circuit ,switchin means and eliminate the. possibility of a s ort circuit. f y f Posts 18 are ixed to the front of the base plate and a cover 19 is fastened over the base latel b screws 2O which turn into these posts. otata lle in the center of the cover is a spindle or arbor 21.0n` the louter end of which is a knob 22 by meansfof which the arbor `may be turned. An insulating block 23 is fixed on the inner end of this arbor so as to turn therewith when the knob is turned. Springwashers 24 are arranged between this blockV and the inside of the cover so that while the block is free to turn-there will'be no looseness. AFastened to one face of this insulating block lis a conductin plate 2liv that has a slotted wingkl 6 vat one en and an extension 27 at the :ot

end. A stud 28 is attached to this extension pivoted on this stud is a switching blade Fastened to one side of the insulatin block is a conducting 30 that at one enV has a contact screw 31. astened to the other lside of the block is a conducting win 32 bearing a contact screw 33. The thin swit hing lblade 29 that is electrically connected with the wing 26 extends between the degree as long as the heating current'is on,-

wings .carried byl the two Contact screws 31 and'33 carried by the win s 30 and 32. The front end of the'switching lade is extended over the outer- :face of the graduated segmental plate and provides an indicating pointer 34.

dial plate which it is desired to maintain. To

whatever point the ad'ustment is made the lock are always enlUfa ed by the contacts on the base plate.

en the main switch of the circuit is closed and the current heats the range, oven or other apparatus, as the heat increases itsaction on the thermostatic coil turns the arm 5 upward `until the insulating'stud 8 which the arm carries engages the switching blade and lifts it from contact with the lower screw 39, with which it is always 'normally in contact, into engagementwith the upper screw 31 and this, through the mechanism usually employed and well known, causes the current to be cut oi.

As the temperature drops, owing to the interruption of thecurrent How, the thermostatic coil turns the arm. down and (allows the switching blade to drop back into contact with the lower screw and again cause the current to be turned on, By this means rthe current'is turned on and olf and as there are no spring tensions to be overcome, the thermo-l stat1c arm only being required to lift the light switching blade, the device is very eiiicient and the temperature of the range, oven or other apparatus, is m intained .very closely to the desired degree. he temperature rises to the degree indicated b .the pointer 34 'at-` the end of a switching b ade wherever that pointer is set, and remains at practically that l and the degreeof heat at any moment is infrom" being dicated by the pointer 7 at the end of tlie arm that is actuated by the therxnostatic coil,v The pin 17 on the 'contact 14 engages the ends of the slot in the wing 26 and preventsthe parts turned soV far as. to cause a short circuit. Y f

-The device is readily applied to the side wall of electrically heated apparatus sothat the temperature conditions at all times,mayA eeen, and the circuit contacts are' be clear yf ade so esto be positive and without danger o disruption.l 1

ported by the base plate, a thermostatic coil with one end connected with the spindle and the other end fixed with relation to the base plate, an arm fixed to the spindle, a cover adapted to be fastened to the base plate, an

arbor rotatably supported by t-he cover, means l for rotating the arbor, three conductors rotatable with the arbor and engaged by the stationary contacts on the base, and a switching blade pivotally carried by one of said conductors and extending between the other conductors and into the path of apart of the arm that is actuated by the thermostatic coil, whereby the switching blade may be adjusted to the desired degree of heat and the arm will engage the blade and move it from engagement with one conductor into engagement with the other conductor. f

2. A' thermostatic control for electric circuits comprising a base plate, a curved index plate fixed to the base plate, means for the at- 4tachment of circuit wires and yielding contacts electrically connected therewith, fixed to the base plate, a tubular stem extending from the base plate, a spindle rotatably supported by the base. plate and extending into said stem, 'a thermostatic coil with one end connected with the spindle and the other end connected with the-stem, an armtlixed to the y spindle and carrying a stud` a cover adapted to bevfastened to the base plate, an arborgrotatably supported by thecover, means forro# tating the arbor, three conductors rotatable with the arbor and engaged by the stationary contacts onjthe base, anda switching blade pivotally carried by one of said conductors and extending between the other conductors and into the path of the stud on the arm thatj is actuated by the thermostatic coil, whereby the switching blade may be adjusted to the desired degree 'of heat and the stud on the arm will engage the blade and move it from engagement with one conductor into engagement with the other conductor.

3. A thermostatic control forelectric circuits comprising a base plate,- a curved index plate xed to the base plate, means for the attachment of circuit wires and yielding contacts electrically connected therewith, fixed 'tothe base platefa tubular stem extending from the base late, a spindle rotatably s upported by the ase plate and extending into said stem, a thermostatic coil with one end connected with the vspindle and the other endV las connected with the stem, an arm fixed to the spindle and'carrying an insulated stud, a:

` cover adapted to be fastened to the base plate, an 'arbor rotatably supported by the` cover,

means for rotating the arbor, an insulating block fixed to the arbor, three conducors attached to said block and engaged by the stationary contacts on the base, contact screws carried by two of said conductors, and a switching blade carried by the other of said conductors and extendin between said screws and into the ath of t e vstud on the arm that is actuatedy y the thermostatic coil, whereb the switching blade may be adjusted to the esired degree of heat and the stud on nthe arm will engage the blade and move it from engagement with one contact .screw into engagement with the othery contact screw. r

4. A thermostatic control for electric circuits comprisin a base plate, a curved index plate fixed to t e base plate, means for the attachment of circuit wires and yielding contacts electrically connected therewith, fixed to the base plate, a tubular stem extending from the base plate, a spindle rotatably supported by the ase plate and extending int'o said stem, a thermostatic coil with one end connected with the spindle and the otherl end connected with the stem, an armnfixed to the s indl and extending in front of the index p ate, 'a cover adapted 4to be fastened to the ase plate, an arbor rotatably supported by the cover, means for rotating the arbor, an insulating block ixed to thel arbor, three conductors attached to said block and engaged by the stationary contacts on the base, and a switchin blade pivotally carried by one of said con uctors and extending between the other of said conductors into the path of a part of the arm that 'is actuated b the thermostatic Icoil and also in front o the index plate, whereby the switching blade may be adjusted to the` desired degree of heat and the arm will 'engage the blade and ymove it from engagement withone conductor into engagement with the other conductor.

5. A thermostatc control for electric ciron the base, a switchin blade pivotally carried by one of said con uctors and extending between the other conductors and into the path "of a part of the arm that is actuated by thethermostatic coil, and means for rotat ing said conductors and switchin blade.

6. A thermostatic control for e ectric circuits comprising a base plate, a curved index plate'fixed' to the base plate, means for the attachment of circuit wires and yielding contacts electrically connected therewith, fixed to the base plate, a.. tubular stem extending from the base late, a spindle rotatably supported by the ase plate and extending into ysaid stem, a thermostatic coil with one end connected with the spindle and the other end connected with the stem, an arm fixed to the spindle and extending in front of the index plate, a cover adapted tofbe fastened-to the ase plate, an arbor rotatably supported by the cover, means for rotating the arbor, an`

insulating piece fixed to the arbor, three conductors attached to said insulating piece, and pivotally mounted switching means extending into the path of a part of said arm tht is actuated by thelthermostatic coil, whereby said switching means maybe adjusted to the desired degree of heat and said arm will engage said switching means and cause it to change the vcircuit from one conductor to another conductor.

" ALBERT E. VVHITTIER. 

